The present invention relates to a planar or areal textile structure with improved heat retention which is to be applied as clothing material or in other applications where a dry, warm micro climate is to be achieved or maintained at the skin surface of the human body. Heat retention is, in the context of this invention, to be considered as representative of all other physiological properties of the respective planar textile structure. These are substantially influenced by the moisture passage resistance of the material.
The heat retention of a planar textile structure generally increases with increasing thickness. In parallel with increasing thickness, the resistance to the passage of moisture also increases, with the result that textiles considered in themselves as warming can cause the skin to be covered with uncomfortable perspiration after they have been worn for a short time. The thickness of the planar textile structures is, therefore chosen so that at a given nominal temperature, satisfactory removal of the moisture formed is ensured in addition to adequate heat retention. The compromise thus arrived at leads to difficulties if the outside ambient temperature deviates distinctly from the noted nominal temperature. In this context, it can be assumed that a feeling of comfort is generally provided only if the average skin temperature does not fall below 32.degree. C., with isolated deviations of .+-.4.degree. C. being allowed in the vicinity of certain zones. The perspiration coverage of the skin surface must, in addition, be less than 30% if a feeling of comfort is to be provided.